engleski

Rate dependent fracture behaviour of adhesively bonded joints

Standard small-scale peel tests, such as the impact wedge-peel (IWP-ISO 11343) and T-peel tests are often employed to analyse the fracture behaviour of structural adhesives. The current work aims to examine the behaviour of adhesively bonded joints under various loading rates by conducting a series of peel tests and simulating the results from such tests numerically. In all tests, thin sheets of aluminium alloy substrates were bonded together using 'XD4600' and 'XD1493' structural epoxy-adhesives. Numerical modelling of the tests was conducted using the Finite Volume (FV) method. For this purpose, transient, 3D, procedures were developed including a newly developed contact model and a cohesive zone (CZ) model as a local failure criterion. The CZ model was defined using two materials parameters, the adhesive fracture energy, G c, and the maximum cohesive stress, σ m. In order to measure the adhesive fracture energy tapered double cantilever beam (TDCB) tests were performed, whereas the value of σ m was estimated from the stress-strain curves at corresponding rates and taken to be the ultimate tensile strength (UTS). Numerical analysis of the tests was conducted in order to calibrate the traction separation curves at various rates, and to examine the stick-slip crack behaviour which appeared in TDCB specimens with 'XD4600' adhesive tested at high rates. The calibrated CZ curves were then used in the prediction of failures in the IWP specimens. Work on modelling T-peel tests is currently in progress.

Adhesive; cohesive zone model; finite volume method; impact wedge peel test; TDCB

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